Manufacture of 1,6-hexanediol from butadiene

Abstract

1,6-Hexanediol is manufactured by hydroformylation of 1,3-butadiene by a process wherein an acetal of pent-3-en-1-al is formed in a first hydroformylation step in the presence of lower alkanols or alkanediols and of rhodium catalysts, and is then converted into 1,6-hexanediol in a second hydroformylation step in the presence of cobalt catalysts, followed by hydrogenation.

I claim: 
     
       1. A process for the manufacture of 1,6-hexanediol by hydroformylation of 1,3-butadiene, wherein, in a first hydroformylation stage, 1,3-butadiene is reacted with carbon monoxide and hydrogen at from 70° to 130°C and from 50 to 600 atmospheres in the presence of a rhodium complex which contains carbon monoxide and a tertiary organic phosphine or tertiary organic phosphite and a halogen atom as ligands, and with an alkanol or alkanediol of 1 to 4 carbon atoms, the rhodium compound is removed, the pent-3-en-1-al-acetal thus obtained is subjected to a second hydroformylation stage, either in the hydroformylation mixture from the first stage after the rhodium compound is removed or after isolation therefrom, with carbon monoxide and hydrogen at from 120° to 220°C and from 20 to 120 atmospheres in the presence of a cobalt carbonyl complex modified with a tertiary organic phosphine, the hydroformylation product thus obtained is hydrogenated by conventional methods in the presence of a hydrogenation catalyst at elevated temperature and superatmospheric pressure, and the 1,6-hexanediol produced is isolated, also by conventional methods. 
     
     
       2. A process as claimed in claim 1, wherein the first hydroformylation stage is carried out in the presence of an alkanol, the resulting pent-3-en-1-al-dialkylacetal is isolated and trans-acetalized with an alkane diol by conventional methods, and the cyclic acetal of the pentenal thus obtained is subjected to the second hydroformylation step. 
     
     
       3. A process as claimed in claim 2, wherein 1,3-propanediol is used as the alkanediol.